This application relates to the art of valves and, more particularly, to valves used in vehicle air brake systems. The invention is particularly applicable to an exhaust valve assembly and will be particularly described with reference thereto. However, it will be appreciated that the invention has broader aspects and may be used in other valve assemblies.
A known type of exhaust valve assembly used on vehicle air brake systems includes a housing having supply, delivery and exhaust ports. A flexible diaphragm is positioned in the housing between the exhaust and supply ports for closing the exhaust port when air pressure is supplied to the supply port for delivery past the diaphragm to the delivery port. When air pressure is supplied to the delivery port in the absence of air pressure at the supply port, the diaphragm moves away from the exhaust port and closes the supply port so that air flows from the delivery port through the exhaust port.
Operation of an exhaust valve in the manner described frequently results in very high frequency vibration of the diaphragm which produces a very loud noise. This vibration and loud noise is commonly referred to as "horning". The vibration of the diaphragm also tends to reduce the air flow rate through the exhaust port.
It would be desirable to have an exhaust valve assembly of the type described wherein vibration of the diaphragm was minimized.